JP2018087997A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the level of a sudden density variation after toner bottle replacement.SOLUTION: An image forming apparatus includes: a development device; toner supply means for supplying toner from a toner bottle to the development device; toner density detection means for detecting information on toner density in the development device; a control part for controlling a normal mode for determining a toner supply amount by the toner supply means to be executable on the basis of a detection result of an inductance sensor; a residual amount detection part in the toner bottle; and a toner bottle sensor. The control part determines whether to immediately permit an image formation operation on the basis of a detection result of the toner bottle sensor after inhibiting the image formation operation on the basis of a detection result of the toner bottle sensor, and executes a supply restriction mode for restricting a toner supply amount by the toner supply means more than the normal mode during a prescribed initial period after permission in the case of permitting the image formation operation.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer.

  Some image forming apparatuses using a conventional two-component developer replenish toner using a toner bottle in order to maintain the charging characteristics of the toner. When the toner in the toner bottle runs out, it is replaced with a new toner bottle. In Japanese Patent Laid-Open No. 2004-260688, the fact that the toner in the toner bottle has run out (no toner) is detected by detecting the TD ratio of the two-component developer in the developing container with the toner density sensor, and indicating that there is no toner in accordance with the value of the toner density sensor. to decide. Then, after the toner bottle is replaced, a toner concentration recovery sequence for recovering the toner concentration is executed. In the toner density recovery sequence, it is determined whether or not a new toner bottle has been replaced according to the value of the toner density sensor.

JP 2005-62848 A

  The problem with the toner density recovery sequence is that the image forming apparatus cannot be used immediately after the toner bottle is replaced. For the user who replaces the toner bottle, the fact that the image forming apparatus cannot be used immediately after the replacement can be stressful. For this reason, from the viewpoint of usability, it is desired that the image forming apparatus can be used immediately after replacement.

  However, if the image formation is permitted without performing the toner density recovery sequence, the replenishment is performed in a state where the TD ratio is lowered. For this reason, in the same replenishment sequence as usual, the replenishment amount is large, so the TD ratio rises rapidly, and the change in toner charging characteristics increases. In this case, in the image formation immediately after the replacement, the density change per sheet becomes large, and the user can easily recognize the color variation. Moreover, when the TD ratio rises rapidly, an overshoot that becomes higher than the target value of the TD ratio may occur. In order to lower the TD ratio, it is necessary to wait for toner consumption due to image formation, which becomes higher than the target value of the TD ratio for a predetermined period.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can quickly form an image after the replacement of the toner bottle and can suppress the level of rapid density fluctuation after the replacement.

  In order to solve the above problems, a typical configuration of an image forming apparatus according to the present invention includes a developing device that develops an electrostatic latent image formed on an image carrier using toner and a magnetic carrier, and a replenishing toner. A toner replenishing means for replenishing toner from the toner bottle containing the toner to the developing device, a toner concentration detecting means for detecting information on the toner concentration in the developing device, and the toner based on the detection result of the toner concentration detecting means. A control unit that controls to execute a normal mode for determining a toner replenishment amount by a replenishment unit, a remaining amount detection unit that detects information about the remaining amount in the toner bottle, and information for determining replacement of the toner bottle In the image forming apparatus having an exchange detecting means for detecting the image forming apparatus, the control unit prohibits an image forming operation based on a detection result of the remaining amount detecting unit, and then It is determined whether to permit the image forming operation immediately based on the detection result of the change detection unit, and when the image forming operation is permitted, the toner replenishing unit performs the toner replenishment unit more than the normal mode in a predetermined initial period after the permission. A replenishment restriction mode for restricting a toner replenishment amount is executed.

  According to the present invention, the transition of the TD ratio after the toner bottle replacement can be made gradual, the target value of the TD ratio can be suppressed from being greatly exceeded, and the level of density fluctuation can be suppressed.

FIG. 2 is a configuration diagram of an image forming unit according to the first embodiment. 1 is a configuration diagram of an image forming apparatus according to a first embodiment. FIG. 3 is a configuration diagram of a toner bottle according to the first embodiment. FIG. 6 is a diagram illustrating a transition of a toner replenishment amount immediately before no toner in a toner bottle. (A) It is a figure which shows TD ratio transition immediately before the toner absence in the conditions of 5% of image ratios. (B) It is a figure which shows transition of the rotation frequency of the replenishment motor just before toner absence on the conditions of 5% of image ratios. FIG. 6 is a diagram illustrating a change in toner replenishment amount after toner bottle replacement. (A) It is a figure which shows TD ratio transition after toner bottle replacement | exchange on the conditions of 5% of image ratios. FIG. 7B is a diagram illustrating a change in the number of rotations of the replenishing motor after the toner bottle replacement under the condition of an image ratio of 5%. FIG. 5 is a flowchart illustrating toner supply control according to the first embodiment. (A) It is a figure which shows TD ratio transition after toner bottle replacement | exchange on the conditions of 5% of image ratios concerning 1st Embodiment. (B) It is a figure which shows transition of the rotation frequency of the replenishment motor after replacement | exchange of a toner bottle on the conditions of 5% of image ratios concerning 1st Embodiment. FIG. 10 is a flowchart illustrating toner supply control according to a second embodiment.

[First embodiment]
A first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 2 is a configuration diagram of the image forming apparatus according to the present embodiment.

  As shown in FIG. 2, the image forming apparatus 1000 according to the present embodiment includes four image forming units IP of yellow, magenta, cyan, and black. Since each image forming unit IP has the same configuration, three image forming units IP are omitted in FIG.

  In each image forming unit IP, the photosensitive drum (image carrier) 1 charged by the charging roller 11 is irradiated with laser light corresponding to the image information from the scanner 12 to form an electrostatic latent image. The electrostatic latent image is developed by the developing device 2 with each color toner as a toner image of each color. The developed toner images of the respective colors are primarily transferred onto the intermediate transfer belt 51 by the primary transfer roller 14. The transfer residual toner remaining on the photosensitive drum 1 after the primary transfer is removed by the cleaning device 15.

  On the other hand, the sheet P stored in the feeding cassette 60 is conveyed to the secondary transfer portion T2 by the pickup roller 61, the conveyance roller 62, and the registration roller 41. The secondary transfer portion T <b> 2 is a nip portion where the intermediate transfer belt 51 is nipped by the secondary transfer inner roller 39 and the secondary transfer outer roller 40. The toner image is secondarily transferred on the sheet P at the secondary transfer portion T2. The sheet P is heated and pressed by the fixing device 90 to fix the toner image, and is discharged outside the image forming apparatus. The transfer residual toner remaining on the intermediate transfer belt 51 after the secondary transfer is removed by the cleaning device 50.

(Image forming unit IP)
FIG. 1 is a configuration diagram of the image forming unit IP. As shown in FIG. 1, the developing device 2 includes a developing chamber 212 and a stirring chamber 211. The developing chamber 212 and the stirring chamber 211 are partitioned by a partition wall 213 extending in the vertical direction. The developing device 2 uses a two-component developer composed of a nonmagnetic toner and a magnetic carrier.

  A nonmagnetic developing sleeve 232 is disposed in the developing chamber 212. A five-pole magnet 231 is fixedly disposed in the developing sleeve 232. A first conveying screw 222 is disposed in the developing chamber 212. The first conveying screw 222 stirs and conveys the developer in the developing chamber 212.

  A second conveying screw 221 is disposed in the stirring chamber 211. The second conveying screw 221 agitates and conveys the replenishing toner supplied from the toner bottle 8 and the developer already in the developing device 2 to make the toner concentration of the developer uniform. An agitation chamber 211 is provided with an inductance sensor (toner concentration detection means) 26. The inductance sensor 26 detects the toner concentration (TD ratio) of the developer.

  The developer moves through the developing chamber 212 and the stirring chamber 211 through a developer passage (not shown) provided at both ends of the partition wall 213. The developing sleeve 232 and the first and second conveying screws 222 and 221 are driven by the developing drive motor 27.

  The developer in the developing device 2 is restrained by the magnetic force of the pumping magnetic pole N <b> 3 and is conveyed by the rotation of the developing sleeve 232. The developer is sufficiently restrained by the cut magnetic pole S <b> 2 and the thickness of the developer is regulated by the regulation blade 25. Then, the developer is transported to the developing region facing the photosensitive drum 1 as the transport magnetic pole N1 and the developing sleeve 232 rotate. The developer forms magnetic spikes by the developing pole S1 in the developing area, and only the toner is transferred to the electrostatic latent image on the photosensitive drum 1 by the developing bias applied to the developing sleeve 232, and the surface of the photosensitive drum 1 A toner image corresponding to the electrostatic latent image is formed.

  In the developing device 2, the toner bottle 8 is detachable. FIG. 3 is a configuration diagram of the toner bottle 8. As shown in FIGS. 1 and 3, the lower toner conveying screw 82 replenishes the toner contained in the toner bottle 8 to the developing device 2 from the replenishing port 85. The upper toner conveying screw 81 conveys the toner on the upper part. The screws 82 and 81 are rotated by the replenishment motor 73. The screws 82 and 81 and the replenishment motor 73 constitute toner replenishing means.

  The rotation of the replenishment motor 73 can be detected by the rotation detection unit 74 in units of one screw rotation. The CPU 101 of the control unit 100 drives the supply motor 73 to rotate a predetermined number of times. A toner bottle sensor (replacement detection means) 86 for determining the presence or absence of the toner bottle 8 is disposed above the toner bottle 8.

(Toner supply control)
Due to the development of the electrostatic latent image, the toner density of the developer in the developing device 2 decreases. Therefore, the control unit 100 performs control (toner supply control) for supplying toner from the toner bottle 8 to the developing device 2. Thereby, the toner density and image density of the developer are controlled as constant as possible. That is, after the control unit prohibits the image forming operation based on the detection result of the inductance sensor (remaining amount detection unit) 26, the control unit immediately permits the image forming operation based on the detection result of the toner bottle sensor (exchange detection means) 86. Decide if you want to. When the image forming operation is permitted, a replenishment restriction mode that restricts the amount of toner replenishment more than the normal mode is executed in a predetermined initial period after the permission.

  The replenishment amount at the time of forming the Nth image in the normal mode will be described below. In the present embodiment, the Nth image calculated from the following equation 3 from the video count supply amount M_Vc (N) calculated from the following equation 1 and the induct supply amount M_Indc (N) calculated from the following equation 2. The toner replenishment amount M (N) is calculated (determined). Then, toner replenishment control is performed with the number of rotations B of the replenishment motor 73 calculated from the following equation 4.

M_Vc (N) = Vc × A_Vc (Formula 1)
Vc: Video count value A_Vc: Coefficient video count value Vc is calculated from the image information of the Nth output. The video count value Vc changes according to the image ratio, and is the video count value Vc = 1023 when an image having an image ratio of 100% (entire solid black) is output.

M_Indc (N) = (TD_target−TD_Indc (N−1)) × A_Indc (Expression 2)
TD_Indc (N−1): TD ratio TD_target calculated from the detection result of the inductance sensor 26 in the (N−1) th sheet: target TD ratio A_Indc: coefficient

  The coefficients A_Vc and A_Indc are recorded in the ROM 102 in advance. The value of A_Indc is set so that M_Indc = 300 mg when TD_Indc is 1% or more lower than TD_target (TD_target−TD_Indc ≦ 1%). In this embodiment, when recording in the RAM 103, when the TD ratio is 8.0%, recording is performed with a value of 8.0, and the unit of the toner replenishment amount is managed in mg. Further, it is recorded in the ROM 102 with the setting of A_Indc = 300. The reason for setting A_Indc = 300 is to stably shift the TD ratio even in an image having a high image ratio and a high toner consumption.

M (N) = M_Vc (N) + M_Indc (N) + M_remain (N−1) (Equation 3)
M_remain (N-1) is the remaining supply amount that cannot be supplied by the previous supply (N-1th sheet). The reason why the remaining replenishment amount occurs is that replenishment is performed in units of one rotation of the screw, so that a replenishment amount less than one rotation remains as the remaining replenishment amount. When M <0, M = 0 is set.

B = M (N) / T (Expression 4)
The amount T to which the lower toner conveying screw 82 rotates once and is replenished to the developing device is recorded in the ROM 102 in advance. The decimal part of B is rounded down and only the positive part is used. The replenishment motor 73 is rotationally driven for the Nth sheet by B calculated by Expression 4. In the present embodiment, due to the limitation on the rotation speed of the replenishment motor 73, B = 5 is set as the maximum value,
M_remain = M (N) −B × T (Expression 5)
The remaining replenishment amount M_remain calculated in (1) is replenished at the next replenishment.
Although the present embodiment has been described with reference to the configuration in which replenishment is performed based on the inductor output and the video count information, the replenishment control method is not limited to this. For example, the toner density in the developing device may be detected based on a density measurement patch formed on the drum, and replenishment control may be performed based on the detection result.

(Empty determination and replacement determination of toner bottle 8)
A method for determining that the toner in the toner bottle 8 runs out (toner bottle 8 is empty) by the control unit 100 will be described. In this embodiment, when the TD ratio (TD_Indc) detected for the Nth sheet is 1% or more lower than the target TD ratio (TD_target) for three consecutive sheets, there is no toner in the toner bottle 8 (toner bottle 8 Is empty).

  When it is determined that the toner bottle 8 is empty, a toner bottle replacement instruction “Please replace the toner bottle” is displayed on the display 300, and the image forming operation is prohibited. Further, the value of the remaining supply amount M (remain) is set to 0, and the past history is reset. The toner bottle 8 is determined to be empty when the replenishment by the replenishment motor 73 and the development drive motor 27 are driven and the detection result of the inductance sensor 26 after replenishment does not change. Also good.

  The replacement of the toner bottle is determined based on a signal from the toner bottle sensor 86 in a state where the instruction to replace the toner bottle is issued on the display device 300. Specifically, in the state where the instruction to replace the toner bottle is given on the display device 300, it is detected that the toner bottle 8 is once removed, and then it is detected that there is no toner bottle. If detected, it is determined that the toner bottle 8 has been replaced.

  In the state where the toner bottle replacement instruction is issued, a message “Have you replaced the toner bottle?” Is displayed on the display 300 and the user presses OK to determine that the toner bottle 8 has been replaced. May be. Further, a base (such as a resistance element that burns out when energized) that can be determined to be new is attached to the toner bottle 8, and it may be determined that the toner bottle 8 has been replaced based on the signal value. The replacement determination of the toner bottle 8 is not limited to the above configuration, and a known replacement detection method can be employed. In addition, in this embodiment, the empty determination of the toner bottle 8 is determined based on the inductive output value using the inductance sensor (remaining amount detection unit) 26 that detects information regarding the remaining amount in the toner bottle. It is not limited to the configuration. This can also be replaced by various known toner remaining amount detection methods.

(Problems of toner replenishment control after toner bottle replacement)
FIG. 4 is a graph showing the transition of the toner replenishment amount immediately before the toner bottle 8 is out of toner. FIG. 5A is a diagram showing a TD ratio transition immediately before the absence of toner under an image ratio of 5%. FIG. 5B is a diagram showing a change in the number of rotations of the replenishment motor 73 immediately before the absence of toner under the condition of an image ratio of 5%.

  As shown in FIGS. 4, 5A, and 5B, when the toner replenishment amount is reduced, the toner replenishment amount is increased by increasing the rotation speed of the replenishment motor 73 as the TD ratio decreases. Since the TD ratio is not recovered, the TD ratio is further reduced and no toner is used.

  FIG. 6 is a graph showing the transition of the toner replenishment amount after the toner bottle replacement. FIG. 7A is a diagram showing a TD ratio transition after toner bottle replacement under the condition of an image ratio of 5%. FIG. 7B is a graph showing the transition of the number of rotations of the replenishment motor 73 after the toner bottle replacement under the condition of an image ratio of 5%.

  As shown in FIGS. 6, 7A, and 7B, the remaining supply amount M (remain) is set to 0 when there is no toner. For this reason, the number of rotations B of the first replenishment motor 73 after the toner bottle replacement is 0. However, since the TD ratio is low, the amount of induct replenishment increases, and the number of rotations B of the replenishment motor 73 immediately increases.

  The toner replenishment amount after replacement of the toner bottle has returned to a level before the replenishment amount decreases, although there is some fluctuation. For this reason, a lot of toner is replenished in the developing device, and the TD ratio detected by the inductance sensor 26 increases rapidly after the fifth sheet when the replenished toner reaches the inductance sensor 26, and the target TD ratio ( The target value) is greatly exceeded 8%.

(Toner replenishment control after toner bottle replacement in this embodiment)
The replenishment restriction mode after toner bottle replacement according to the present embodiment will be described. In this embodiment, the toner bottle initial period is provided after determining that the toner bottle has been replaced. In the toner bottle initial period, the coefficient (A_Indc) used when calculating the induct replenishment amount M_Indc is set to a coefficient (A_Indc_init) smaller than the normal value. In this embodiment, the coefficient A_Indc_init = 100 mg for the toner bottle initial period. The induct replenishment amount M_Indc (N) in the toner bottle initial period is calculated by the following formula 6 instead of the formula 2.

M_Indc (N) = (TD_target−TD_Indc (N−1)) × A_Indc_init (Expression 6)
The release timing of the toner bottle initial period is set when the difference value between the detection result (TD ratio) of the inductance sensor 26 and the target TD ratio is within a predetermined range. In the present embodiment, it is assumed that the TD ratio (TD_Indc) detected for the Nth sheet satisfies TD_target−TD_Indc (N) ≦ 0.1 (%). At this timing, the coefficient is returned from A_Indc_init to the coefficient A_Indc.

  The value is not limited to 0.1 (%), and other values may be used in consideration of the TD ratio transition. Also, the release timing of the initial period of the toner bottle may be when a predetermined time has elapsed, when a predetermined number of images are formed, or the like. Alternatively, the toner bottle initial period may be canceled when a predetermined amount of toner is replenished and the cumulative number of rotations of the replenishment motor 73 after determining that the toner bottle has been replaced exceeds a predetermined value. In addition, when the TD ratio after a predetermined period after it is determined that the toner bottle has been replaced is lower than the target TD ratio by a predetermined value or more, if the toner concentration recovery sequence for recovering the TD ratio is executed, the initial period of the toner bottle is set. You may cancel.

  FIG. 8 is a flowchart illustrating toner supply control according to this embodiment. As shown in FIG. 8, when it is determined that the toner bottle 8 has been replaced (S1), image formation is permitted (S2). At this time, the toner bottle initial period is set (S3), and the coefficient used when calculating the induct replenishment amount M_Indc is switched from A_Indc to A_Indc_init (S4).

  N-th image formation is started, and after completion of the image formation, it is determined whether or not to cancel the toner bottle initial period (S7). If it is determined in S7 that the toner bottle initial period is not canceled, the setting of the toner bottle initial period is continued (S8), and the process returns to S5. If it is determined in S7 that the toner bottle initial period is cancelled, the toner bottle initial period is canceled (S9), and the coefficient used when calculating the induct replenishment amount: M_Indc is switched from A_Indc to A_Indc_init (S10). Then, the toner supply control after the replacement of the toner bottle is finished, and the normal toner supply control is returned to.

(effect)
FIG. 9A is a diagram showing a TD ratio transition after toner bottle replacement under the condition of an image ratio of 5% according to the first embodiment. FIG. 9B is a diagram illustrating a change in the number of rotations of the replenishment motor 73 after the toner bottle replacement under the condition of the image ratio of 5% according to the first embodiment. 9A and 9B, the broken line indicates toner supply control without correction without setting the toner bottle initial period. A solid line indicates toner replenishment control with correction according to the present exemplary embodiment for setting the toner bottle initial period.

  As shown in FIGS. 9A and 9B, as in the present embodiment, the toner replenishment amount is reduced compared to the normal mode by reducing the induct replenishment amount in the initial period of the toner bottle after the toner bottle replacement. To be limited. As a result, the transition of the number of toner replenishment (the number of rotations B of the replenishment motor 73) is moderate, and the increase in the TD ratio is also moderate. Moreover, unlike the broken line, the target TD ratio is not greatly exceeded. Therefore, according to this embodiment, the TD ratio transition after the toner bottle replacement can be moderated, and the level of density fluctuation can be suppressed.

[Second Embodiment]
Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. The same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  In the first embodiment, one coefficient is used as the coefficient used when calculating the induct replenishment amount M_Indc in the initial period of the toner bottle. In this embodiment, two types of coefficients are used for calculating the induct replenishment amount M_Indc in the initial period of the toner bottle, and a coefficient to be used is selected based on the magnitude relationship between TD_target and TD_Indc (N−1).

  When TD_target ≧ TD_Indc (N−1), that is, when the TD ratio is smaller than the target value, A_Indc and A_Indc_init are used. On the other hand, when TD_target <TD_Indc (N−1), that is, when the TD ratio is higher than the target value, C_Indc and C_Indc_init are used. In this embodiment, A_Indc = C_Indc = C_Indc_init = 300 mg and A_Indc_init = 100 mg. In other words, Expression 2 and Expression 6 are the following Expression 2A and Expression 6A when TD_target ≧ TD_Indc (N−1), and the following Expression 2C and Expression 6C when TD_target <TD_Indc (N−1). Become.

M_Indc (N) = (TD_target−TD_Indc (N−1)) × A_Indc (Equation 2A)
M_Indc (N) = (TD_target−TD_Indc (N−1)) × A_Indc_init (Expression 6A)
M_Indc (N) = (TD_target−TD_Indc (N−1)) × C_Indc (Equation 2C)
M_Indc (N) = (TD_target−TD_Indc (N−1)) × C_Indc_init (Expression 6C)

  As described above, two types of coefficients are used, and A_Indc_init is set to a value smaller than the other coefficients. As a result, as in the first embodiment, when the TD ratio is lower than the target value, the TD ratio transition after the toner bottle replacement can be moderated, and the level of density fluctuation can be suppressed. On the other hand, in the setting of the first embodiment, the TD ratio does not increase from the target value (TD_target <TD_Indc (N-1)), but the TD ratio may increase from the target value depending on conditions. In this case, by using C_Indc_init = 300 mg, while the toner supply from the toner bottle 8 is suppressed, it is possible to wait for the TD ratio to reach the target value as the toner is consumed by image formation.

  Note that the values of A_Indc, A_Indc_init, C_Indc, and C_Indc_init are not limited to the above values. Any value can be used as long as the TD ratio transition can be made moderate when the TD ratio is lower than the target value, and the toner supply from the toner bottle 8 can be suppressed when the D ratio is higher than the target value. Moreover, regarding changing the value of C_Indc_init, there is no particular limitation regarding changing while watching the stability of the TD ratio.

  FIG. 10 is a flowchart illustrating toner supply control according to this embodiment. As shown in FIG. 10, in this embodiment, the coefficients used in the magnitude relationship between TD_target and TD_Indc (N-1) are selected in S4 and S10 in the flowchart of FIG. 8, and other than that in the first embodiment. The same control is performed.

[Third embodiment]
Next, a third embodiment of the image forming apparatus according to the present invention will be described. The same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, instead of changing the coefficient as in the first and second embodiments, or in addition to the configuration for changing the coefficient, the following configuration is provided. That is, the upper limit of the induct replenishment amount M_Indc of the first and second embodiments is limited (a maximum value is set). Thereby, even if the difference value between TD_target and TD_Indc (N−1) is large, the induct replenishment amount M_Indc does not need to be excessively increased. Therefore, as in the first and second embodiments, the TD ratio transition after the toner bottle replacement can be moderated, and the density fluctuation level can be suppressed.

  In the present embodiment, in the toner bottle initial period, the upper limit of the induct replenishment amount M_Indc is set to 100 mg, but other set values may be set in accordance with the transition of the TD ratio. In addition, in the normal time other than the initial period of the toner bottle, it is less necessary to set a limit on the induct replenishment amount M_Indc. However, when the limit is set, the upper limit value in the limit mode is smaller than the upper limit value in the normal mode. To do. In this way, accidental oversupply can be suppressed.

[Fourth embodiment]
Next, a description will be given of a fourth embodiment of the image forming apparatus according to the present invention. The same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

In the present embodiment, in the first and second embodiments, TD_target is changed to a smaller value than usual only in the initial period of the toner bottle after the toner bottle replacement. Specifically, TD_target is changed from 8.0% to 7.7% only during the initial period of the toner bottle after the toner bottle replacement. Then, after the toner bottle initial period ends, TD_target is returned from 7.7% to 8.0%.
As a result, for example, when TD_target before replacement of the toner bottle is 8.0% and TD_Indc = 6.9% and no toner comes out, the difference value between TD_target and TD_Indc is changed from 1.1% to 0.8%. can do. Therefore, the difference value between TD_target and TD_Indc (N−1) can be reduced, and the induct replenishment amount M_Indc can be reduced. For this reason, as in the first to third embodiments, the TD ratio transition after the toner bottle replacement can be moderated, and the level of density fluctuation can be suppressed.

B ... Number of rotations IP ... Image forming unit M ... Toner replenishment amount P ... Sheet 1 ... Photosensitive drum 2 ... Developing device 8 ... Toner bottle 26 ... Inductance sensor (toner density detection means, remaining amount detection unit)
27: Development drive motor 73 ... Supply motor (toner supply means)
74: Rotation detection unit 81: Upper toner conveying screw (toner supply means)
82 ... Lower toner conveying screw (toner supply means)
85 ... Supply port 86 ... Toner bottle sensor (replacement detection means)
DESCRIPTION OF SYMBOLS 100 ... Control part 221 ... 2nd conveyance screw 222 ... 1st conveyance screw 232 ... Development sleeve 300 ... Display device 1000 ... Image forming apparatus

In order to solve the above problems, a typical configuration of an image forming apparatus according to the present invention includes a developing device that develops an electrostatic latent image formed on an image carrier using toner and a magnetic carrier, and a replenishing toner. A toner replenishing unit for replenishing toner from the toner bottle containing the toner to the developing device, a toner concentration detecting unit for detecting information on toner density in the developing device, and a replenishing toner amount to be replenished by the toner replenishing unit. A determining unit, and a control unit for prohibiting an image forming operation when the toner concentration in the developing device falls below a set value based on an output of the toner concentration detecting unit, and transmitting information regarding replacement of the toner bottle ; in the image forming apparatus having a replacement detecting means for detecting the replacement of the toner bottle, after which the control unit has transmitted the information about the exchange of the toner bottle When the replacement detection unit detects replacement of the toner bottle and starts an image forming operation when the toner density in the developing device is lower than a set value, the determination unit replaces the toner bottle. The replenishment toner amount is determined so that the replenishment toner amount after the predetermined period elapses from the replenishment toner amount determined by the determining means after the predetermined period elapses .

Claims (8)

A developing device for developing the electrostatic latent image formed on the image carrier using toner and a magnetic carrier;
Toner replenishing means for replenishing toner from a toner bottle containing replenishing toner to the developing device;
Toner density detecting means for detecting information relating to toner density in the developing device;
A control unit that controls to execute a normal mode for determining a toner replenishment amount by the toner replenishing unit based on a detection result of the toner density detecting unit;
A remaining amount detecting unit for detecting information on the remaining amount in the toner bottle;
In an image forming apparatus having an exchange detection means for detecting information for judging the replacement of the toner bottle,
The control unit determines whether to permit the image forming operation immediately based on the detection result of the replacement detection unit after prohibiting the image forming operation based on the detection result of the remaining amount detection unit, and In the image forming apparatus, the image forming apparatus executes a replenishment restriction mode for restricting a toner replenishment amount by the toner replenishing unit more than the normal mode in a predetermined initial period after the authorization. The amount of toner replenished by the toner replenishing means is calculated by multiplying the difference value between the detection result of the toner density detecting means and the target value by a coefficient,
The image forming apparatus according to claim 1, wherein the coefficient in the replenishment restriction mode is smaller than the coefficient in the normal mode. The coefficient in the replenishment restriction mode is provided in two types, when the detection result of the toner density detection unit is smaller than the target value and when the detection result of the toner density detection unit is larger than the target value,
The coefficient when the detection result of the toner concentration detection unit is smaller than a target value is smaller than the coefficient when the detection result of the toner concentration detection unit is larger than a target value. Image forming apparatus.   4. The image forming apparatus according to claim 1, wherein a maximum value of a toner replenishment amount by the toner replenishing unit is set in the replenishment restriction mode.
The image forming apparatus according to claim 2, wherein the target value in the replenishment restriction mode is set to a value smaller than the target value in the normal mode.   6. The toner bottle initial period after detecting the replacement of the toner bottle by the toner bottle detecting means is until the difference value falls within a predetermined range. The image forming apparatus according to claim 1.   6. The toner bottle initial period after detecting the replacement of the toner bottle by the toner bottle detecting means is until a predetermined amount of toner is supplied from the toner supplying means. The image forming apparatus according to any one of the above. The control unit executes a toner concentration recovery sequence for recovering the toner concentration of the two-component developer in the developing device when the difference value is equal to or greater than a predetermined value after a predetermined period has elapsed since the toner bottle was replaced. And
6. The toner bottle initial period after detecting the replacement of the toner bottle by the toner bottle detecting means is until the toner density recovery sequence is executed. The image forming apparatus according to item 1.